Renal symptomatology in patients with acute intermittent porphyria. A population-based study

Objective. Can renal insufficiency in subjects with acute intermittent porphyria (AIP) be due solely to AIP? Design. A population-based study. Subjects. Subjects with AIP greater than or equal to 18 years of age (n = 386) in the four most northerly counties of Sweden. Interventions. Screening with creatinine clearance at 24 h. Patients below the lower reference level underwent a repeat clearance test and, if still low, also chromEDTA clearance. Results. 286 (74%) subjects performed the creatinine clearance test and in 57 clearance was low; the second clearance proved normal in 23 who were then excluded. Eighteen subjects with other possible medical reasons for renal insufficiency, ethical reasons or refusing further examinations were also excluded. The 16 remaining subjects with no explanation for their renal insufficiency other than AIP were then studied in detail. All 14 women, mean age 52 years, and two uraemic men, 58 and 67 years, had manifest AIP. Twelve patients had hypertension (HT) and four were normotensive in spite of renal insufficiency. Histological findings of renal biopsies revealed diffuse glomerulosclerotic and interstitial changes with additional ischaemic lesions. Conclusion. Protracted vasospasm in attacks of AIP may be a cause of renal lesions. This is discussed.